In January 1967, Mao instructed the rebel factions in Shanghai to seize power from party and government organizations. The struggle for power was fierce. In February the short-lived 'Shanghai People's Commune' was established, led by Zhang Chunqiao, member of the Gang of Four. This poster was issued by the Shanghai Workers' Revolutionary Rebel General Headquarters, Zhang's base of power. It is an announcement of an "oath taking rally", 14 February 1967, at Culture Square (文化广场), then renamed Revolution Square (革命广场).